A rear combination lamp to be disposed in a rear portion of a vehicle body on either side has been known to include a plurality of types of lamps having different functions within a lighting chamber defined by a housing and an outer lens that covers the opening of the housing. Such lamps having different functions may include a tail lamp, a turn indicator lamp, a back-up lamp, and the like.
Such a rear combination lamp is demanded to be reduced in size. In order to do so, some rear combination lamps have been configured to employ a light emitting element such as a light emitting diode (LED) as at least one of the plurality of types of lamps, for example, as a light source for a tail lamp. In these lamps, further employed is a light guiding lens that is configured to guide light emitted from the light emitting element to be illuminated with the light, as if the light guiding lens itself can emit light. This type of lighting unit can be found in a publication of Japanese Patent Application Laid-Open Nos. 2013-161697 and 2013-243068.
FIG. 1 is a cross-sectional view illustrating part of a vehicle lighting unit that causes a light guiding lens to be illuminated with light emitted from a light emitting element. The light guiding lens 111 can have an aesthetic portion 111B and cuts 111b formed in a rear surface of the aesthetic portion 111B. The light guided through the light guiding lens 111 while totally reflected by the inner surface of the light guiding lens 111 can be reflected by the cuts 111b to exit through the surface (light exiting face) of the light guiding lens 111. By doing so, the aesthetic portion 111B of the light guiding lens 111 can be illuminated with light when it is viewed from its front side as if the aesthetic portion 111B itself emit light.
In the light guiding lens 111 illustrated in FIG. 1, since the region r1 of the light guiding lens 111 is a thick portion, lens cuts 111b provided in the rear surface of the aesthetic portion 111B cannot be extended from the formed lens cut 111b and formed within that region r1 for taking out the light through the front surface of the region r1. When the aesthetic portion 111B of the light guiding lens 111 has a largely curved portion, any cuts 111b cannot be formed in the inner surface of the region r2 illustrated in FIG. 1 due to the design of a metal mold to be used for molding the light guiding lens 111. Accordingly, the light is totally reflected at the regions r1+r2 where any cuts 111b are not formed in the rear surface thereof, and thus, the light cannot exit through these regions and the light emission region is narrowed to deteriorate the aesthetic feature as the lighting unit when emitting light.